There is, and will continue to be, advances and changes in how enterprises conduct business. Whether these advances and changes occur through growing competition and globalization, mergers and acquisitions, or a revamping of business models, the key for success will often depend on how quickly the enterprise's information technology (IT) organization can adapt to evolving business needs. Therefore, a major challenge to these enterprises is how they handle change.
For organizations to enable business agility, they must ensure that enterprise applications are not only high-performance business engines driving efficiencies, but also that they become flexible building blocks of future business systems. A recent promising solution has risen in the form of services. A service, such as a Web service, application, or program, represents a self-contained, self-describing piece of application functionality that can be found and accessed by other applications. A service is self-contained because the application using the service does not have to depend on anything other than the service itself, and self-describing because all the information on how to use the service can be obtained from the service itself. The descriptions are centrally stored and accessible through standard mechanisms.
A service may be described by a WSDL (Web Services Description Language) document. WSDL is an XML format (also providing an XML Schema) for describing services as a set of endpoints operating on messages containing either document-oriented or procedure-oriented information. For example, the WSDL description of the service may describe the service (or web service) including how to instantiate the web service, how to interact with the web service, the format of any calls to the web service, and the format of any data sent to the web service. When a client application is developed to interact with the web service, it must comply with the WSDL description to interact with the web service. Likewise, the web service should comply with its WSDL description. At present, two specifications specify WSDL (see WSDL version 1.1 and WSDL version 2.0 at www.w3.org).